Cable drum cut list calculator
Paste the cable run lengths and the drums you have. The calculator decides which run comes off which drum, uses part drums and offcuts first, and shows the balance after every cut, what is left on each drum and what you need to buy.
What the example shows
The example is 14 runs of one cable type, 915 m to cut once the 1 m allowance is added to each, against three pieces of stock: a full 500 m drum, a part drum with 180 m on it, and a 45 m offcut.
The offcut and the part drum are used first, because cutting them costs nothing extra. The full drum is then filled down to its 2 m reserve. Stock covers 718 m; the rest goes on one 250 m drum to buy, which leaves 53 m on it for reuse. Scrap across the whole plan is 7 m, and most of that is the 2 m reserve kept on each drum, which shows as the leftover when a drum is used right down to it.
How does the calculator decide which run goes on which drum?
It puts as much of the cable as possible on the drums you already have, then prefers the plan that leaves every drum it cuts from either used down to its reserve or holding a length long enough to reuse, and that avoids opening a full drum when part drums and offcuts can take the runs.
- Fill the drums one at a time. Offcuts first, then part drums, then full drums. Each takes the combination of remaining runs that fills it most exactly, not simply the longest runs.
- Improve the whole plan. Runs are moved and swapped between drums while that lowers the cost. Every metre that has to be bought counts ten times a metre of scrap. Opening a full drum counts as 30 m of scrap or a tenth of the drum, whichever is more, because an unopened drum can often go back to the supplier or on to the next job.
- Buy what stock cannot cover. The remaining runs are grouped onto new drums, each the shortest length on your list that holds its runs plus the reserve. A run longer than your longest drum gets a special length.
- Order the cuts. On each drum the longest run is cut first, and the balance after each cut is what the crew should see on the drum.
This is the allocation Drumplan uses for a whole cable schedule. The calculator runs it for one cable type at a time.
What allowances should you add to cable cut lengths?
Add a fixed length to every cut for the cable you lose at the ends, add a percentage only if the schedule lengths do not already include spare, and keep a small reserve on every drum. Set them to your own site practice; the defaults are only a starting point.
| Setting | What it covers | Default |
|---|---|---|
| Allowance per cut | Added to every run: the pulling end and the cut-off lost at each cut. | 1 m (3 ft) |
| Percentage | Added to schedule lengths. Leave it at 0 if the schedule already includes spare: Pathnovo's cable schedule template, for example, builds in 10% spare and about 2 m per end for terminations. | 0% |
| Reserve per drum | Kept back on every drum, not on offcuts, for length tolerance and measuring error. | 2 m (6 ft) |
| Shortest reusable offcut | A leftover at least this long goes back into stock for another run; anything shorter is scrap. | 15 m (50 ft) |
| Drum lengths you can buy | The lengths you can order for this cable. Check what your supplier stocks for the size before you order. | 100, 250, 500, 1,000 m |
How much cable is wasted when cutting from drums?
There is no standard figure. Estimators allow a percentage for waste, and the waste you can control on a drum job is the leftover too short to use on any other run.
Allowances vary by trade and job: in one long-running Electrician Talk thread about building wire, estimators said they figure 5%, 10% and 15%. For armoured power cable the percentage matters less than where the tails end up. A 20 m leftover of large copper cable is expensive to scrap, and the same 20 m planned onto the right run costs nothing. The calculator shows the leftover on every drum and says whether it is long enough to reuse, so you can see the real waste before anyone cuts.
To cut the waste further: use part drums and offcuts before opening full drums, buy drum lengths that suit the runs rather than the largest drum, and record the real length of every cut so the next plan starts from what is actually on the drum.
What the calculator does not do
- It plans one cable type at a time. For a cable schedule with several types, use the calculator once per type, or the planner.
- It does not work out how much cable fits on a drum from its dimensions, or pulling tension.
- It does not remember anything. Copy the result to Excel, or plan the job in Drumplan.
Plan the whole schedule, not one type
Drumplan does the same allocation for every cable type in your cable schedule at once. Import the schedule and the drum register as Excel or CSV, and it prints a drum card for each drum, exports the drum schedule and the order list to Excel, and keeps the balances true as the site records cuts. Planning is free, with no account, and your spreadsheets are never uploaded.
Sources
- Pathnovo, free cable schedule template (cable length including 10% spare, about 2 m per end): pathnovo.com, checked 28 September 2026.
- Electrician Talk, "wire waste" thread, July 2009 (estimators figuring 5%, 10% and 15%): electriciantalk.com, checked 28 September 2026.
- The allocation: Drumplan's planning engine, the same code the app uses.